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Strapazzon G, Taboni A, Dietrichs ES, Luks AM, Brugger H. Avalanche burial pathophysiology - a unique combination of hypoxia, hypercapnia and hypothermia. J Physiol 2024. [PMID: 39073871 DOI: 10.1113/jp284607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 06/17/2024] [Indexed: 07/30/2024] Open
Abstract
For often unclear reasons, the survival times of critically buried avalanche victims vary widely from minutes to hours. Individuals can survive and sustain organ function if they can breathe under the snow and maintain sufficient delivery of oxygen and efflux of carbon dioxide. We review the physiological responses of humans to critical avalanche burial, a model which shares similarities and differences with apnoea and accidental hypothermia. Within a few minutes of burial, an avalanche victim is exposed to hypoxaemia and hypercapnia, which have important effects on the respiratory and cardiovascular systems and pose a major threat to the central nervous system. As burial time increases, an avalanche victim also develops hypothermia. Despite progressively reduced metabolism, reduced oxygen and increased carbon dioxide tensions may exacerbate the pathophysiological consequences of hypothermia. Hypercapnia seems to be the main cause of cardiovascular instability, which, in turn, is the major reason for reduced cerebral oxygenation despite reductions in cerebral metabolic activity caused by hypothermia. 'Triple H syndrome' refers to the interaction of hypoxia, hypercapnia and hypothermia in a buried avalanche victim. Future studies should investigate how the respiratory gases entrapped in the porous snow structure influence the physiological responses of buried individuals and how haemoconcentration, blood viscosity and cell deformability affect blood flow and oxygen delivery. Attention should also be devoted to identifying strategies to prolong avalanche survival by either mitigating hypoxia and hypercapnia or reducing core temperature so that neuroprotection occurs before the onset of cerebral hypoxia.
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Affiliation(s)
- Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Department of Medicine - DIMEM, University of Padova, Padova, Italy
| | - Anna Taboni
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | | | - Andrew M Luks
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Hermann Brugger
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
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2
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Ribeiro LDJA, Bastos VHDV, Coertjens M. Breath-holding as model for the evaluation of EEG signal during respiratory distress. Eur J Appl Physiol 2024; 124:753-760. [PMID: 38105311 DOI: 10.1007/s00421-023-05379-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
PURPOSE Research describes the existence of a relationship between cortical activity and the regulation of bulbar respiratory centers through the evaluation of the electroencephalographic (EEG) signal during respiratory challenges. For example, we found evidences of a reduction in the frequency of the EEG (alpha band) in both divers and non-divers during apnea tests. For instance, this reduction was more prominent in divers due to the greater physiological disturbance resulting from longer apnea time. However, little is known about EEG adaptations during tests of maximal apnea, a test that voluntarily stops breathing and induces dyspnea. RESULTS Through this mini-review, we verified that a protocol of successive apneas triggers a significant increase in the maximum apnea time and we hypothesized that successive maximal apnea test could be a powerful model for the study of cortical activity during respiratory distress. CONCLUSION Dyspnea is a multifactorial symptom and we believe that performing a successive maximal apnea protocol is possible to understand some factors that determine the sensation of dyspnea through the EEG signal, especially in people not trained in apnea.
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Affiliation(s)
- Lucas de Jesus Alves Ribeiro
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil
- Brain Mapping and Functionality Laboratory, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
| | - Victor Hugo do Vale Bastos
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil
- Postgraduate Program in Biomedical Sciences, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
- Brain Mapping and Functionality Laboratory, Universidade Federal do Delta do Parnaíba, Piauí, Brazil
| | - Marcelo Coertjens
- Physiotherapy Department, Universidade Federal do Delta do Parnaíba, Av. São Sebastião, CEP: 64.202-020, Parnaíba, PI, 2819, Brazil.
- Postgraduate Program in Biomedical Sciences, Universidade Federal do Delta do Parnaíba, Piauí, Brazil.
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3
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Bourdas DI, Geladas ND. Physiological responses during static apnoea efforts in elite and novice breath-hold divers before and after two weeks of dry apnoea training. Respir Physiol Neurobiol 2024; 319:104168. [PMID: 37797907 DOI: 10.1016/j.resp.2023.104168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/30/2023] [Accepted: 10/01/2023] [Indexed: 10/07/2023]
Abstract
This study examined the effect of breath-hold (BH) training on apnoeic performance in novice BH divers (NBH:n = 10) and compared them with data from elite BH divers (EBH:n = 11). Both groups performed 5-maximal BHs (PRE). The NBH group repeated this protocol after two weeks of BH training (POST). The NBH group during BH efforts significantly increased red blood cell concentration (4.56 ± 0.16Mio/μl) by 5.06%, hemoglobin oxygen saturation steady state duration (110.32 ± 29.84 s) by 15.48%, and breath-hold time (BHT:144.19 ± 47.35 s) by 33.77%, primarily due to a 59.70% increase in struggle phase (71.85 ± 30.89 s), in POST. EBH group exhibited longer BHT (283.95 ± 36.93 s) and struggle-phase (150.10 ± 34.69 s) than NBH (POST). Elite divers recorded a higher peak MAP (153.18 ± 12.28 mmHg) compared to novices (PRE:123.70 ± 15.65 mmHg, POST:128.30 ± 19.16 mmHg), suggesting that a higher peak MAP is associated with a better BHT. The concurrent abrupt increase of diaphragmatic activity and MAP, seen only in the EBH group, suggests a potential interaction. Additionally, apnoea training increases red blood cells concentration in repeated apnoea efforts and increases BH stamina.
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Affiliation(s)
- Dimitrios I Bourdas
- Section of Sport Medicine & Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, Ethnikis Antistasis 41, 17237 Daphni, Greece.
| | - Nickos D Geladas
- Section of Sport Medicine & Biology of Exercise, School of Physical Education and Sports Science, National and Kapodistrian University of Athens, Ethnikis Antistasis 41, 17237 Daphni, Greece
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Persson G, Lodin-Sundström A, Linér MH, Andersson SHA, Sjögreen B, Andersson JPA. Splenic contraction and cardiovascular responses are augmented during apnea compared to rebreathing in humans. Front Physiol 2023; 14:1109958. [PMID: 36960158 PMCID: PMC10028099 DOI: 10.3389/fphys.2023.1109958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/22/2023] [Indexed: 03/09/2023] Open
Abstract
The spleen contracts during apnea, releasing stored erythrocytes, thereby increasing systemic hemoglobin concentration (Hb). We compared apnea and rebreathing periods, of equal sub-maximal duration (mean 137 s; SD 30), in eighteen subjects to evaluate whether respiratory arrest or hypoxic and hypercapnic chemoreceptor stimulation is the primary elicitor of splenic contraction and cardiovascular responses during apnea. Spleen volume, Hb, cardiovascular variables, arterial (SaO2), cerebral (ScO2), and deltoid muscle oxygen saturations (SmO2) were recorded during the trials and end-tidal partial pressure of oxygen (PETO2) and carbon dioxide (PETCO2) were measured before and after maneuvers. The spleen volume was smaller after apnea, 213 (89) mL, than after rebreathing, 239 (95) mL, corresponding to relative reductions from control by 20.8 (17.8) % and 11.6 (8.0) %, respectively. The Hb increased 2.4 (2.0) % during apnea, while there was no significant change with rebreathing. The cardiovascular responses, including bradycardia, decrease in cardiac output, and increase in total peripheral resistance, were augmented during apnea compared to during rebreathing. The PETO2 was higher, and the PETCO2 was lower, after apnea compared to after rebreathing. The ScO2 was maintained during maneuvers. The SaO2 decreased 3.8 (3.1) % during apnea, and even more, 5.4 (4.4) %, during rebreathing, while the SmO2 decreased less during rebreathing, 2.2 (2.8) %, than during apnea, 8.3 (6.2) %. We conclude that respiratory arrest per se is an important stimulus for splenic contraction and Hb increase during apnea, as well as an important initiating factor for the apnea-associated cardiovascular responses and their oxygen-conserving effects.
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Affiliation(s)
- Gustav Persson
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- *Correspondence: Gustav Persson, ; Johan P. A. Andersson,
| | - Angelica Lodin-Sundström
- Department of Health Sciences, Mid Sweden University, Sundsvall, Sweden
- Department of Biology, Lund University, Lund, Sweden
| | - Mats H. Linér
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Samuel H. A. Andersson
- Department of Biology, Lund University, Lund, Sweden
- Department of Clinical Sciences, Malmö, Lund University, Lund, Sweden
| | | | - Johan P. A. Andersson
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- *Correspondence: Gustav Persson, ; Johan P. A. Andersson,
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A century of exercise physiology: key concepts on coupling respiratory oxygen flow to muscle energy demand during exercise. Eur J Appl Physiol 2022; 122:1317-1365. [PMID: 35217911 PMCID: PMC9132876 DOI: 10.1007/s00421-022-04901-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/25/2022] [Indexed: 12/26/2022]
Abstract
After a short historical account, and a discussion of Hill and Meyerhof’s theory of the energetics of muscular exercise, we analyse steady-state rest and exercise as the condition wherein coupling of respiration to metabolism is most perfect. The quantitative relationships show that the homeostatic equilibrium, centred around arterial pH of 7.4 and arterial carbon dioxide partial pressure of 40 mmHg, is attained when the ratio of alveolar ventilation to carbon dioxide flow (\documentclass[12pt]{minimal}
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\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2) is − 21.6. Several combinations, exploited during exercise, of pertinent respiratory variables are compatible with this equilibrium, allowing adjustment of oxygen flow to oxygen demand without its alteration. During exercise transients, the balance is broken, but the coupling of respiration to metabolism is preserved when, as during moderate exercise, the respiratory system responds faster than the metabolic pathways. At higher exercise intensities, early blood lactate accumulation suggests that the coupling of respiration to metabolism is transiently broken, to be re-established when, at steady state, blood lactate stabilizes at higher levels than resting. In the severe exercise domain, coupling cannot be re-established, so that anaerobic lactic metabolism also contributes to sustain energy demand, lactate concentration goes up and arterial pH falls continuously. The \documentclass[12pt]{minimal}
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\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2 decreases below − 21.6, because of ensuing hyperventilation, while lactate keeps being accumulated, so that exercise is rapidly interrupted. The most extreme rupture of the homeostatic equilibrium occurs during breath-holding, because oxygen flow from ambient air to mitochondria is interrupted. No coupling at all is possible between respiration and metabolism in this case.
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Taboni A, Fagoni N, Fontolliet T, Moia C, Vinetti G, Ferretti G. A closed-loop approach to the study of the baroreflex dynamics during posture changes at rest and at exercise in humans. Am J Physiol Regul Integr Comp Physiol 2021; 321:R960-R968. [PMID: 34643104 DOI: 10.1152/ajpregu.00167.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that during rapid uptilting at rest, due to vagal withdrawal, arterial baroreflex sensitivity (BRS) may decrease promptly and precede the operating point (OP) resetting, whereas different kinetics are expected during exercise steady state, due to lower vagal activity than at rest. To test this, eleven subjects were rapidly (<2 s) tilted from supine (S) to upright (U) and vice versa every 3 min, at rest and during steady-state 50 W pedaling. Mean arterial pressure (MAP) was measured by finger cuff (Portapres) and R-to-R interval (RRi) by electrocardiography. BRS was computed with the sequence method both during steady and unsteady states. At rest, BRS was 35.1 ms·mmHg-1 (SD = 17.1) in S and 16.7 ms·mmHg-1 (SD = 6.4) in U (P < 0.01), RRi was 901 ms (SD = 118) in S and 749 ms (SD = 98) in U (P < 0.01), and MAP was 76 mmHg (SD = 11) in S and 83 mmHg (SD = 8) in U (P < 0.01). During uptilt, BRS decreased promptly [first BRS sequence was 19.7 ms·mmHg-1 (SD = 5.0)] and was followed by an OP resetting (MAP increase without changes in RRi). At exercise, BRS and OP did not differ between supine and upright positions [BRS was 7.7 ms·mmHg-1 (SD = 3.0) and 7.7 ms·mmHg-1 (SD = 3.5), MAP was 85 mmHg (SD = 13) and 88 mmHg (SD = 10), and RRi was 622 ms (SD = 61) and 600 ms (SD = 70), respectively]. The results support the tested hypothesis. The prompt BRS decrease during uptilt at rest may be ascribed to a vagal withdrawal, similarly to what occurs at exercise onset. The OP resetting may be due to a slower control mechanism, possibly an increase in sympathetic activity.
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Affiliation(s)
- Anna Taboni
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland
| | - Nazzareno Fagoni
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,AAT Brescia, Department of Anaesthesiology, Intensive Care and Emergency Medicine, Spedali Civili University Hospital, Brescia, Italy
| | - Timothée Fontolliet
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Christian Moia
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Giovanni Vinetti
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Guido Ferretti
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
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7
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Bouten J, De Bock S, Bourgois G, de Jager S, Dumortier J, Boone J, Bourgois JG. Heart Rate and Muscle Oxygenation Kinetics During Dynamic Constant Load Intermittent Breath-Holds. Front Physiol 2021; 12:712629. [PMID: 34366898 PMCID: PMC8339880 DOI: 10.3389/fphys.2021.712629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 06/17/2021] [Indexed: 11/18/2022] Open
Abstract
Introduction: Acute apnea evokes bradycardia and peripheral vasoconstriction in order to conserve oxygen, which is more pronounced with face immersion. This response is contrary to the tachycardia and increased blood flow to muscle tissue related to the higher oxygen consumption during exercise. The aim of this study was to investigate cardiovascular and metabolic responses of dynamic dry apnea (DRA) and face immersed apnea (FIA). Methods: Ten female volunteers (17.1 ± 0.6 years old) naive to breath-hold-related sports, performed a series of seven dynamic 30 s breath-holds while cycling at 25% of their peak power output. This was performed in two separate conditions in a randomized order: FIA (15°C) and DRA. Heart rate and muscle tissue oxygenation through near-infrared spectroscopy were continuously measured to determine oxygenated (m[O2Hb]) and deoxygenated hemoglobin concentration (m[HHb]) and tissue oxygenation index (mTOI). Capillary blood lactate was measured 1 min after the first, third, fifth, and seventh breath-hold. Results: Average duration of the seven breath-holds did not differ between conditions (25.3 s ± 1.4 s, p = 0.231). The apnea-induced bradycardia was stronger with FIA (from 134 ± 4 to 85 ± 3 bpm) than DRA (from 134 ± 4 to 100 ± 5 bpm, p < 0.001). mTOI decreased significantly from 69.9 ± 0.9% to 63.0 ± 1.3% (p < 0.001) which is reflected in a steady decrease in m[O2Hb] (p < 0.001) and concomitant increase in m[HHb] (p = 0.001). However, this was similar in both conditions (0.121 < p < 0.542). Lactate was lower after the first apnea with FIA compared to DRA (p = 0.038), while no differences were observed in the other breath-holds. Conclusion: Our data show strong decreases in heart rate and muscle tissue oxygenation during dynamic apneas. A stronger bradycardia was observed in FIA, while muscle oxygenation was not different, suggesting that FIA did not influence muscle oxygenation. An order of mechanisms was observed in which, after an initial tachycardia, heart rate starts to decrease after muscle tissue deoxygenation occurs, suggesting a role of peripheral vasoconstriction in the apnea-induced bradycardia. The apnea-induced increase in lactate was lower in FIA during the first apnea, probably caused by the stronger bradycardia.
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Affiliation(s)
- Janne Bouten
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Sander De Bock
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Gil Bourgois
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Sarah de Jager
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jasmien Dumortier
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.,Centre of Sports Medicine, Ghent University Hospital, Ghent, Belgium
| | - Jan G Bourgois
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.,Centre of Sports Medicine, Ghent University Hospital, Ghent, Belgium
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Bouten J, Bourgois JG, Lootens L, Boone J. Acute apnea and white blood cell count: A biphasic response formal comment on 'Hematologic changes after short term hypoxia in non-elite apnea divers under voluntary dry apnea conditions'. PLoS One 2021; 16:e0253584. [PMID: 34260608 PMCID: PMC8279404 DOI: 10.1371/journal.pone.0253584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/09/2021] [Indexed: 11/18/2022] Open
Affiliation(s)
- Janne Bouten
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
| | - Jan G. Bourgois
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
- Centre of Sports Medicine, Ghent University Hospital, Ghent, Belgium
| | - Leen Lootens
- Doping Control Laboratory, Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium
- Doping Control Laboratory, Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
- * E-mail:
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Baroreflex responses during dry resting and exercise apnoeas in air and pure oxygen. Eur J Appl Physiol 2020; 121:539-547. [PMID: 33151437 PMCID: PMC7862076 DOI: 10.1007/s00421-020-04544-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/26/2020] [Indexed: 12/02/2022]
Abstract
Purpose We analysed the characteristics of arterial baroreflexes during the first phase of apnoea (φ1). Methods 12 divers performed rest and exercise (30 W) apnoeas (air and oxygen). We measured beat-by-beat R-to-R interval (RRi) and mean arterial pressure (MAP). Mean RRi and MAP values defined the operating point (OP) before (PRE-ss) and in the second phase (φ2) of apnoea. Baroreflex sensitivity (BRS, ms·mmHg−1) was calculated with the sequence method. Results In PRE-ss, BRS was (median [IQR]): at rest, 20.3 [10.0–28.6] in air and 18.8 [13.8–25.2] in O2; at exercise 9.2[8.4–13.2] in air and 10.1[8.4–13.6] in O2. In φ1, during MAP decrease, BRS was lower than in PRE-ss at rest (6.6 [5.3–11.4] in air and 7.7 [4.9–14.3] in O2, p < 0.05). At exercise, BRS in φ1 was 6.4 [3.9–13.1] in air and 6.7 [4.1–9.5] in O2. After attainment of minimum MAP (MAPmin), baroreflex resetting started. After attainment of minimum RRi, baroreflex sequences reappeared. In φ2, BRS at rest was 12.1 [9.6–16.2] in air, 12.9 [9.2–15.8] in O2. At exercise (no φ2 in air), it was 7.9 [5.4–10.7] in O2. In φ2, OP acts at higher MAP values. Conclusion In apnoea φ1, there is a sudden correction of MAP fall via baroreflex. The lower BRS in the earliest φ1 suggests a possible parasympathetic mechanism underpinning this reduction. After MAPmin, baroreflex resets, displacing its OP at higher MAP level; thus, resetting may not be due to central command. After resetting, restoration of BRS suggests re-establishment of vagal drive.
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Taboni A, Fagoni N, Fontolliet T, Grasso GS, Moia C, Vinetti G, Ferretti G. Breath holding as an example of extreme hypoventilation: experimental testing of a new model describing alveolar gas pathways. Exp Physiol 2020; 105:2216-2225. [PMID: 32991750 DOI: 10.1113/ep088977] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/28/2020] [Indexed: 12/14/2022]
Abstract
NEW FINDINGS What is the central question of this study? We modelled the alveolar pathway during breath holding on the hypothesis that it follows a hypoventilation loop on the O2 -CO2 diagram. What is the main finding and its importance? Validation of the model was possible within the range of alveolar gas compositions compatible with consciousness. Within this range, the experimental data were compatible with the proposed model. The model and its characteristics might allow predictions of alveolar gas composition whenever the alveolar ventilation goes to zero; for example, static and dynamic breath holding at the surface or during ventilation/intubation failure in anaesthesia. ABSTRACT According to the hypothesis that alveolar partial pressures of O2 and CO2 during breath holding (BH) should vary following a hypoventilation loop, we modelled the alveolar gas pathways during BH on the O2 -CO2 diagram and tested it experimentally during ambient air and pure oxygen breathing. In air, the model was constructed using the inspired and alveolar partial pressures of O2 ( P I O 2 and P A O 2 , respectively) and CO2 ( P IC O 2 and P AC O 2 , respectively) and the steady-state values of the pre-BH respiratory exchange ratio (RER). In pure oxygen, the model respected the constraint of P AC O 2 = - P A O 2 + P I O 2 . To test this, 12 subjects performed several BHs of increasing duration and one maximal BH at rest and during exercise (30 W cycling supine), while breathing air or pure oxygen. We measured gas flows, P A O 2 and P AC O 2 before and at the end of all BHs. Measured data were fitted through the model. In air, P I O 2 = 150 ± 1 mmHg and P IC O 2 = 0.3 ± 0.0 mmHg, both at rest and at 30 W. Before BH, steady-state RER was 0.83 ± 0.16 at rest and 0.77 ± 0.14 at 30 W; P A O 2 = 107 ± 7 mmHg at rest and 102 ± 8 mmHg at 30 W; and P AC O 2 = 36 ± 4 mmHg at rest and 38 ± 3 mmHg at 30 W. By model fitting, we computed the RER during the early phase of BH: 0.10 [95% confidence interval (95% CI) = 0.08-0.12] at rest and 0.13 (95% CI = 0.11-0.15) at 30 W. In oxygen, model fitting provided P I O 2 : 692 (95% CI = 688-696) mmHg at rest and 693 (95% CI = 689-698) mmHg at 30 W. The experimental data are compatible with the proposed model, within its physiological range.
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Affiliation(s)
- Anna Taboni
- Department of Anaesthesiology, Pharmacology, Intensive Care and Emergencies, University of Geneva, Geneva, Switzerland
| | - Nazzareno Fagoni
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Timothée Fontolliet
- Department of Anaesthesiology, Pharmacology, Intensive Care and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | | | - Christian Moia
- Department of Anaesthesiology, Pharmacology, Intensive Care and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Giovanni Vinetti
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Guido Ferretti
- Department of Anaesthesiology, Pharmacology, Intensive Care and Emergencies, University of Geneva, Geneva, Switzerland.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
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11
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Hold your breath: peripheral and cerebral oxygenation during dry static apnea. Eur J Appl Physiol 2020; 120:2213-2222. [PMID: 32748010 DOI: 10.1007/s00421-020-04445-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/17/2020] [Indexed: 01/17/2023]
Abstract
PURPOSE Acute breath-holding deprives the human body from oxygen. In an effort to protect the brain, the diving response is initiated, coupling several physiological responses. The aim of this study was to describe the physiological responses to apnea at the cardiac, peripheral and cerebral level. METHODS 31 physically active subjects (17 male, 14 female, 23.3 ± 1.8 years old) performed a maximal static breath-hold in a seated position. Heart rate (HR), muscle and cerebral oxygenation (by means of near-infrared spectroscopy, NIRS) were continuously measured. RM MANOVA's were used to identify changes in HR, peripheral (mTOI) and cerebral (cTOI) tissue oxygenation and oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin during apnea. RESULTS Average apnea duration was 157 ± 41 s. HR started decreasing after 10 s (p < 0.001) and dropped on average by 27 ± 14 bpm from baseline (p < 0.001). mTOI started decreasing 10 s after apnea (p < 0.001) and fell by 8.6 ± 4.0% (p < 0.001). Following an immediate drop after 5 s (p < 0.001), cTOI increased continuously, reaching a maximal increase of 3.7 ± 2.4% followed by a steady decrease until the end of apnea. cTOI fell on average 5.4 ± 8.3% below baseline (p < 0.001). CONCLUSION During apnea, the human body elicits several protective mechanisms to protect itself against the deprivation of oxygen. HR slows down, decreasing O2 demand of the cardiac muscle. The decrease in mTOI and increase in cTOI imply a redistribution of blood flow prioritizing the brain. However, this mechanism is not sufficient to maintain cTOI until the end of apnea.
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Taboni A, Fagoni N, Moia C, Vinetti G, Ferretti G. Gas exchange and cardiovascular responses during breath-holding in divers. Respir Physiol Neurobiol 2019; 267:27-34. [PMID: 31201868 DOI: 10.1016/j.resp.2019.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/15/2019] [Accepted: 06/12/2019] [Indexed: 12/19/2022]
Abstract
To check whether the evolution of alveolar pressures of O2 (PAO2) and CO2 (PACO2) explains the cardiovascular responses to apnoea, eight divers performed resting apnoeas of increasing duration in air and in O2. We measured heart rate (fH), arterial pressure (AP), and peripheral resistances (TPR) beat-by-beat, PAO2 and PACO2 at the end of each apnoea. The three phases of the cardiovascular response to apnoea were observed. In O2, TPR increase (9 ± 4 mmHg min l-1) and fH decrease (-11 ± 8 bpm) were lower than in air (15 ± 5 mmHg min l-1 and -28 ± 13 bpm, respectively). At end of maximal apnoeas in air, PAO2 and PACO2 were 50 ± 9 and 48 ± 5 mmHg, respectively; corresponding values in O2 were 653 ± 8 mmHg and 55 ± 5 mmHg. At end of phase II, PAO2 and PACO2 in air were 90 ± 13 mmHg and 42 ± 4 mmHg respectively; corresponding values in O2 were 669 ± 7 mmHg and 47 ± 6 mmHg. The PACO2 increase may trigger the AP rise in phase III.
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Affiliation(s)
- Anna Taboni
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, rue Michel Servet 1, CH-1211, Geneva, Switzerland.
| | - Nazzareno Fagoni
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Christian Moia
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, rue Michel Servet 1, CH-1211, Geneva, Switzerland; Department of Basic Neurosciences, University of Geneva, rue Michel Servet 1, CH-1211, Geneva, Switzerland
| | - Giovanni Vinetti
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Guido Ferretti
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, rue Michel Servet 1, CH-1211, Geneva, Switzerland; Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy; Department of Basic Neurosciences, University of Geneva, rue Michel Servet 1, CH-1211, Geneva, Switzerland
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13
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Steinberg F, Doppelmayr M. Neurocognitive Markers During Prolonged Breath-Holding in Freedivers: An Event-Related EEG Study. Front Physiol 2019; 10:69. [PMID: 30792665 PMCID: PMC6374628 DOI: 10.3389/fphys.2019.00069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/21/2019] [Indexed: 01/16/2023] Open
Abstract
Since little is known concerning the psychological, cognitive, and neurophysiological factors that are involved in and important for phases of prolonged breath-holding (pBH) in freedivers, the present study uses electroencephalography (EEG) to investigate event-related neurocognitive markers during pBH of experienced freedivers that regularly train pBH. The purpose was to determine whether the well-known neurophysiological modulations elicited by hypoxic and hypercapnic conditions can also be detected during pBH induced hypoxic hypercapnia. Ten experienced free-divers (all male, aged 35.10 ± 7.89 years) were asked to hold their breath twice for 4 min per instance. During the first pBH, a checker board reversal task was presented and in the second four-min pBH phase a classical visual oddball paradigm was performed. A visual evoked potential (VEP) as an index of early visual processing (i.e., latencies and amplitudes of N75, P100, and N145) and the latency and amplitude of a P300 component (visual oddball paradigm) as an index of cognitive processing were investigated. In a counter-balanced cross-over design, all tasks were once performed during normal breathing (B), and once during pBH. All components were then compared between an early pBH (0–2 min) and a later pBH stage (2–4 min) and with the same time phases without pBH (i.e., during normal breathing). Statistical analyses using analyses of variance (ANOVA) revealed that comparisons between B and pBH yielded no significant changes either in the amplitude and latency of the VEP or in the P300. This indicates that neurocognitive markers, whether in an early visual processing stream or at a later cognitive processing stage, were not affected by pBH in experienced free-divers.
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Affiliation(s)
- Fabian Steinberg
- Department of Sport Psychology, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Michael Doppelmayr
- Department of Sport Psychology, Institute of Sport Science, Johannes Gutenberg-University Mainz, Mainz, Germany.,Centre of Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
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14
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Cardiovascular responses to dry apnoeas at exercise in air and in pure oxygen. Respir Physiol Neurobiol 2018; 255:17-21. [PMID: 29733980 DOI: 10.1016/j.resp.2018.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/26/2018] [Accepted: 05/02/2018] [Indexed: 12/13/2022]
Abstract
If, as postulated, the end of the steady state phase (φ2) of cardiovascular responses to apnoea corresponds to the physiological breaking point, then we may hypothesize that φ2 should become visible if exercise apnoeas are performed in pure oxygen. We tested this hypothesis on 9 professional divers by means of continuous recording of blood pressure (BP), heart rate (fH), stroke volume (QS), and arterial oxygen saturation (SpO2) during dry maximal exercising apnoeas in ambient air and in oxygen. Apnoeas lasted 45.0 ± 16.9 s in air and 77.0 ± 28.9 s in oxygen (p < 0.05). In air, no φ2 was observed. Conversely, in oxygen, a φ2 of 28 ± 5 s duration appeared, during which systolic BP (185 ± 29 mmHg), fH (93 ± 16 bpm) and QS (91 ± 16 ml) remained stable. End-apnoea SpO2 was 95.5 ± 1.9% in air and 100% in oxygen. The results support the tested hypothesis.
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Abstract
Breath-hold diving is practiced by recreational divers, seafood divers, military divers, and competitive athletes. It involves highly integrated physiology and extreme responses. This article reviews human breath-hold diving physiology beginning with an historical overview followed by a summary of foundational research and a survey of some contemporary issues. Immersion and cardiovascular adjustments promote a blood shift into the heart and chest vasculature. Autonomic responses include diving bradycardia, peripheral vasoconstriction, and splenic contraction, which help conserve oxygen. Competitive divers use a technique of lung hyperinflation that raises initial volume and airway pressure to facilitate longer apnea times and greater depths. Gas compression at depth leads to sequential alveolar collapse. Airway pressure decreases with depth and becomes negative relative to ambient due to limited chest compliance at low lung volumes, raising the risk of pulmonary injury called "squeeze," characterized by postdive coughing, wheezing, and hemoptysis. Hypoxia and hypercapnia influence the terminal breakpoint beyond which voluntary apnea cannot be sustained. Ascent blackout due to hypoxia is a danger during long breath-holds, and has become common amongst high-level competitors who can suppress their urge to breathe. Decompression sickness due to nitrogen accumulation causing bubble formation can occur after multiple repetitive dives, or after single deep dives during depth record attempts. Humans experience responses similar to those seen in diving mammals, but to a lesser degree. The deepest sled-assisted breath-hold dive was to 214 m. Factors that might determine ultimate human depth capabilities are discussed. © 2018 American Physiological Society. Compr Physiol 8:585-630, 2018.
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16
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Steinberg F, Pixa NH, Doppelmayr M. Electroencephalographic alpha activity modulations induced by breath-holding in apnoea divers and non-divers. Physiol Behav 2017; 179:90-98. [PMID: 28554527 DOI: 10.1016/j.physbeh.2017.05.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 04/24/2017] [Accepted: 05/25/2017] [Indexed: 10/19/2022]
Abstract
Little is known regarding cortical responses to sustained breath-holding (BH) in expert apnoea divers. The present study therefore investigated electroencephalographic (EEG) alpha activity and asymmetries in apnoea divers (experts) compared to non-divers (novices). EEG of 10 apnoea and 10 non-divers were recorded in the laboratory for either four minutes or for two minutes of BH. Alpha activity and alpha asymmetry (i.e. hemispherical EEG differences) were calculated and compared between expertise level and BH duration. Alpha amplitude in experts significantly decreased at four minutes of BH compared to resting activity, while alpha amplitude significantly decreased in novices only at centro-parietal regions. Alpha-asymmetry analysis revealed that the experts' decrease in alpha at the end of BH was different in the frontal electrodes with the left prefrontal cortex activity higher than that in the right prefrontal cortex. This lateralized pattern reflected differential prefrontal processing of the unique psycho-physiological state of BH.
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Affiliation(s)
- Fabian Steinberg
- Johannes Gutenberg University Mainz, Institute of Sport Science, Department of Sport Psychology, Germany.
| | - Nils Henrik Pixa
- Johannes Gutenberg University Mainz, Institute of Sport Science, Department of Sport Psychology, Germany
| | - Michael Doppelmayr
- Johannes Gutenberg University Mainz, Institute of Sport Science, Department of Sport Psychology, Germany; University of Salzburg, Centre of Cognitive Neuroscience, Austria
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17
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Bringard A, Adami A, Fagoni N, Fontolliet T, Lador F, Moia C, Tam E, Ferretti G. Dynamics of the RR-interval versus blood pressure relationship at exercise onset in humans. Eur J Appl Physiol 2017; 117:619-630. [PMID: 28238048 DOI: 10.1007/s00421-017-3564-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE The dynamics of the postulated phenomenon of exercise baroreflex resetting is poorly understood, but can be investigated using closed-loop procedures. To shed light on some mechanisms and temporal relationships participating in the resetting process, we studied the time course of the relationship between the R-R interval (RRi) and arterial pressure with a closed-loop approach. METHODS On ten young volunteers at rest and during light exercise in supine and upright position, we continuously determined, on single-beat basis, RRi (electrocardiography), and arterial pressure (non-invasive finger pressure cuff). From pulse pressure profiles, we determined cardiac output (CO) by Modelflow, computed mean arterial pressure (MAP), and calculated total peripheral resistance (TPR). RESULTS At exercise start, RRi was lower than in quiet rest. As exercise started, MAP fell to a minimum (MAPm) of 72.8 ± 9.6 mmHg upright and 73.9 ± 6.2 supine, while RRi dropped. The initial RRi versus MAP relationship was linear, with flatter slope than resting baroreflex sensitivity, in both postures. TPR fell and CO increased. After MAPm, RRi and MAP varied in opposite direction toward exercise steady state, with further CO increase. CONCLUSION These results suggest that, initially, the MAP fall was corrected by a RRi reduction along a baroreflex curve, with lower sensitivity than at rest, but eventually in the same pressure range as at rest. After attainment of MAPm, a second phase started, where the postulated baroreflex resetting might have occurred. In conclusion, the change in baroreflex sensitivity and the resetting process are distinct phenomena, under different control systems.
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Affiliation(s)
- Aurélien Bringard
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Alessandra Adami
- Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland.,Division of Respiratory and Critical Care Physiology and Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 W Carson St, Torrance, CA, 90502, USA
| | - Nazzareno Fagoni
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Timothée Fontolliet
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Frédéric Lador
- Service de Pneumologie, Programme Hypertension Pulmonaire, Département des Spécialités de Médecine, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève, Switzerland
| | - Christian Moia
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Enrico Tam
- Dipartimento di Scienze Neurologiche, Biomediche e del Movimento, Università di Verona, Via Felice Casorati 43, 37131, Verona, Italy
| | - Guido Ferretti
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland. .,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland. .,Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy.
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18
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Fagoni N, Breenfeldt Andersen A, Oberholzer L, Haider T, Meinild Lundby AK, Lundby C. Reliability and validity of non-invasive determined haemoglobin mass and blood volumes. Clin Physiol Funct Imaging 2017; 38:240-245. [DOI: 10.1111/cpf.12406] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/07/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Nazzareno Fagoni
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
- Department of Molecular and Translational Medicine; University of Brescia; Brescia Italy
| | - Andreas Breenfeldt Andersen
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
- Department of Nutrition, Exercise and Sports (NEXS); University of Copenhagen; Copenhagen Denmark
| | - Laura Oberholzer
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
| | - Thomas Haider
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
| | - Anne-Kristine Meinild Lundby
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
| | - Carsten Lundby
- Zurich Center of Integrative Human Physiology; Institute of Physiology; University of Zürich; Zürich Switzerland
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19
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Fagoni N, Taboni A, Vinetti G, Bottarelli S, Moia C, Bringard A, Ferretti G. Alveolar gas composition during maximal and interrupted apnoeas in ambient air and pure oxygen. Respir Physiol Neurobiol 2016; 235:45-51. [PMID: 27721037 DOI: 10.1016/j.resp.2016.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 10/05/2016] [Accepted: 10/06/2016] [Indexed: 11/16/2022]
Abstract
INTRODUCTION We tested the hypothesis that the alveolar gas composition at the transition between the steady phase II (φ2) and the dynamic phase III (φ3) of the cardiovascular response to apnoea may lay on the physiological breaking point curve (Lin et al., 1974). METHODS Twelve elite divers performed maximal and φ2-interrupted apnoeas, in air and pure oxygen. We recorded beat-by-beat arterial blood pressure and heart rate; we measured alveolar oxygen and carbon dioxide pressures (PAO2 and PACO2, respectively) before and after apnoeas; we calculated the PACO2 difference between the end and the beginning of apnoeas (ΔPACO2). RESULTS Cardiovascular responses to apnoea were similar compared to previous studies. PAO2 and PACO2 at the end of φ2-interrupted apnoeas, corresponded to those reported at the physiological breaking point. For maximal apnoeas, PACO2 was less than reported by Lin et al. (1974). ΔPACO2 was higher in oxygen than in air. CONCLUSIONS The transition between φ2 and φ3 corresponds indeed to the physiological breaking point. We attribute this transition to ΔPACO2, rather than the absolute PACO2 values, both in air and oxygen apnoeas.
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Affiliation(s)
- Nazzareno Fagoni
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Italy; Dipartimento di Specialità Medico-chirurgiche, Scienze Radiologiche e Sanità Pubblica, Università di Brescia, Italy.
| | - Anna Taboni
- Dipartimento di Scienze Cliniche e Sperimentali, Università di Brescia, Italy
| | - Giovanni Vinetti
- Dipartimento di Scienze Cliniche e Sperimentali, Università di Brescia, Italy
| | - Sara Bottarelli
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Italy
| | - Christian Moia
- Département des Neurosciences Fondamentales, Université de Genève, Switzerland
| | - Aurélién Bringard
- Département des Neurosciences Fondamentales, Université de Genève, Switzerland
| | - Guido Ferretti
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Italy; Département des Neurosciences Fondamentales, Université de Genève, Switzerland
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Ratmanova P, Semenyuk R, Popov D, Kuznetsov S, Zelenkova I, Napalkov D, Vinogradova O. Prolonged dry apnoea: effects on brain activity and physiological functions in breath-hold divers and non-divers. Eur J Appl Physiol 2016; 116:1367-77. [PMID: 27188878 DOI: 10.1007/s00421-016-3390-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE The aim of the study was to investigate the effects of voluntary breath-holding on brain activity and physiological functions. We hypothesised that prolonged apnoea would trigger cerebral hypoxia, resulting in a decrease of brain performance; and the apnoea's effects would be more pronounced in breath-hold divers. METHODS Trained breath-hold divers and non-divers performed maximal dry breath-holdings. Lung volume, alveolar partial pressures of O2 and CO2, attention and anxiety levels were estimated. Heart rate, blood pressure, arterial blood oxygenation, brain tissue oxygenation, EEG, and DC potential were monitored continuously during breath-holding. RESULTS There were a few significant changes in electrical brain activity caused by prolonged apnoea. Brain tissue oxygenation index and DC potential were relatively stable up to the end of the apnoea in breath-hold divers and non-divers. We also did not observe any decrease of attention level or speed of processing immediately after breath-holding. Interestingly, trained breath-hold divers had some peculiarities in EEG activity at resting state (before any breath-holding): non-spindled, sharpened alpha rhythm; slowed-down alpha with the frequency nearer to the theta band; and untypical spatial pattern of alpha activity. CONCLUSION Our findings contradicted the primary hypothesis. Apnoea up to 5 min does not lead to notable cerebral hypoxia or a decrease of brain performance in either breath-hold divers or non-divers. It seems to be the result of the compensatory mechanisms similar to the diving response aimed at centralising blood circulation and reducing peripheral O2 uptake. Adaptive changes during apnoea are much more prominent in trained breath-hold divers.
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Affiliation(s)
- Patricia Ratmanova
- Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia.
| | - Roxana Semenyuk
- Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia
| | - Daniil Popov
- Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia
| | - Sergey Kuznetsov
- Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia
| | - Irina Zelenkova
- Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia.,Russian Olympic Committee Innovation Center, 119991, Luzhnetskaya Embankment 8, Moscow, Russia
| | - Dmitry Napalkov
- Department of Higher Nervous Activity, Faculty of Biology, M.V. Lomonosov Moscow State University, 119234, Leninskie Gory 1/12, Moscow, Russia
| | - Olga Vinogradova
- Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoye Sh., 76A, Moscow, Russia
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Costalat G, Coquart J, Castres I, Joulia F, Sirost O, Clua E, Lemaître F. The oxygen-conserving potential of the diving response: A kinetic-based analysis. J Sports Sci 2016; 35:678-687. [PMID: 27167834 DOI: 10.1080/02640414.2016.1183809] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics [heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation [oxyhaemoglobin ([HbO2]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO2) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (-0.86 bpm.%-1) while HR kinetics in NDs steadily decreased throughout BH (-0.47 bpm.%-1). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower [HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a [tHb] drop that NDs did not at the end of BH (-7.3 ± 3.2 vs. -3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an "oxygen-conserving breaking point" in the human diving response.
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Affiliation(s)
| | - Jeremy Coquart
- a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France
| | - Ingrid Castres
- a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France
| | - Fabrice Joulia
- b UMR MD2, Aix Marseille University and IRBA , Marseille , France
| | - Olivier Sirost
- a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France
| | - Eric Clua
- c NRS-EPHE , USR3278 , Papetoai , French Polynesia
| | - Frédéric Lemaître
- a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France
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Cardiovascular responses to dry resting apnoeas in elite divers while breathing pure oxygen. Respir Physiol Neurobiol 2015; 219:1-8. [PMID: 26253502 DOI: 10.1016/j.resp.2015.07.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/31/2015] [Accepted: 07/31/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE We hypothesized that the third dynamic phase (ϕ3) of the cardiovascular response to apnoea requires attainment of the physiological breaking point, so that the duration of the second steady phase (ϕ2) of the classical cardiovascular response to apnoea, though appearing in both air and oxygen, is longer in oxygen. METHODS Nineteen divers performed maximal apnoeas in air and oxygen. We measured beat-by-beat arterial pressure, heart rate (fH), stroke volume (SV), cardiac output (Q˙). RESULTS The fH, SV and Q˙ changes during apnoea followed the same patterns in oxygen as in air. Duration of steady ϕ2 was 105 ± 37 and 185 ± 36 s, in air and oxygen (p<0.05), respectively. At end of apnoea, arterial oxygen saturation was 1.00 ± 0.00 in oxygen and 0.75 ± 0.10 in air. CONCLUSIONS The results support the tested hypothesis. Lack of hypoxaemia during oxygen apnoeas suggests that, if chemoreflexes determine ϕ3, the increase in CO2 stores might play a central role in eliciting their activation.
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